An active-matrix-addressed liquid crystal display device generally includes an active-matrix substrate on which thin-film transistors (TFTs) are provided as switching elements for respective pixels (and which is sometimes called a “TFT substrate”), a counter substrate on which color filters and other members are arranged (and which is sometimes called a “color filter substrate”), and a liquid crystal layer which is interposed between the active-matrix substrate and the counter substrate. An electric field, of which the intensity is represented by the potential difference between pixel electrodes that are electrically connected to the thin-film transistors and a common electrode, is applied to the liquid crystal layer to change the orientation states of liquid crystal molecules in the liquid crystal layer. In this manner, a display operation can be conducted with the optical transmittance of each pixel controlled.
Various display modes have been proposed and adopted for active-matrix-addressed liquid crystal display devices according to their intended application. Examples of those display modes include a TN (Twisted Nematic) mode, a VA (Vertical Alignment) mode, an IPS (In-Plane-Switching) mode and an FFS (Fringe Field Switching) mode.
Among those liquid crystal display devices, there are ones of which the active-matrix substrate includes two transparent conductive layers that have been formed so as to interpose an inorganic insulating layer between them. The structure of an electrode which is formed by such a pair of transparent conductive layers that interpose an inorganic insulating layer between them will be referred to herein as a “double-layer electrode structure” for the sake of simplicity.
For example, in a general FFS mode, the lower one of the two transparent conductive layers is provided as a common electrode and the upper transparent conductive layer is provided as pixel electrodes with slits as disclosed in Patent Document No. 1. Meanwhile, a configuration in which pixel electrodes are arranged as the lower electrodes and a common electrode with slits is arranged as the upper electrode is also known as disclosed in Patent Document No. 2.